The present invention refers generally to mechanical sealing devices, including or forming a part of equipment comprising a rotating shaft extending through a passage to be sealed. More specifically, the present invention refers to a mechanical sealing device according to the preamble of claim 1, and to a pump according to the preamble of claim 13.
Such a mechanical sealing device can be used in a variety of applications. For instance, such a mechanical sealing device can be used in pumps for pumping a liquid. The first holder element may then be joined to the pump housing via a peripheral thread provided radially outside the first seal element. During operation, possible stresses in the pump housing can be transferred to the first seal surface via the thread, and thus create non planar states and consequently leakage.
By means of the elastomer element, provided between the outer peripheral surface of the first seal element and the inner surface of the first holder element, this problem could be remedied. Such a solution is disclosed in U.S. Pat. No. 3,291,493.
However, with this solution the elastomer element, which frequently is made of rubber, will come into contact with the liquid to be pumped. For hygienic reasons, such contact between the pump liquid and the rubber of the elastomer element is not desired in many applications, such as medical applications or in the food industry.
U.S. Pat. No. 3,291,493 discloses a mechanical sealing device comprising a first machine part and a second machine part. A first sealing ring is connected to the first machine part, and a second sealing ring is connected to the second machine part. The second sealing ring is surrounded by a gasket element extending around an inner corner of the sealing ring.
U.S. Pat. No. 5,758,880 discloses a mechanical sealing device incorporating a similar solution, where a ceramic sealing element is supported by an elastomer element extending around a corner of the sealing element.
EP-A-798499 discloses a further mechanical sealing device, which comprises a rotary seal element mounted on a shaft, and an opposite stationary seal element supported by a holder component via an elastomer ring. The elastomer ring extends also in this case around an inner corner of the stationary seal element.
GB-A-2044862 discloses a mechanical sealing device with a rotating seal element and an opposite stationary seal element supported in a housing via an O-ring.